‘This is the most splendid coup I have seen in this war,’ General von Falkenhorst, the German commander in chief in Norway, remarked with a rueful smile in February 1943 after inspecting the ruins of the seemingly impregnable Norsk Hydro plant. Its destruction by the Special Operations Executive (SOE) deprived Hitler of the supply of heavy water essential for the making of an atomic bomb. Although those involved were all Norwegian, they had been trained, in meticulous detail, in Britain. According to an articulate and influential member of SOE, Norsk provided ‘classic proof of our contention that one aircraft which drops an intelligent and well-trained party can do more damage than a whole fleet of bombers’.